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Multiformat listening test @ ~64kbps: Results, Results and post-test discussion
IgorC
post Apr 12 2011, 00:40
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The test is finished, results are available here:

http://listening-tests.hydrogenaudio.org/igorc/results.html

Summary: CELT/Opus won, Apple HE-AAC is better than Nero HE-AAC, and Vorbis has caught up with Nero HE-AAC.
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C.R.Helmrich
post Apr 12 2011, 20:11
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Thanks for organizing the tests, guys! Sorry for being picky, but I'm not convinced about the analysis. To ease my mind, it would be great if you could comment on the following.

  • Please provide the number of valid results (i.e. listeners) per sample (excluding "27", see below).
  • How did you compute the overall average score of a codec and its confidence intervals? Taking the mean of all listeners' results? That would mean a sample with more listeners (i.e. probably sample01) has a greater influence than the last few samples (which still needed listeners shortly before the end of the test). This is probably not a good approach; weighting each sample equally in the overall score seems to be the way to go for me (but it probably doesn't make a difference here, but still...).
  • Nothing personal, but if a listener like "27" consistently scores in opposite direction as the average (as shown by Igor), a thorough post-screening analysis (like Spearman rank correlation < some value) would - and has to - exclude such results.


Edit: Christoph, why are the samples you uploaded at 96 kHz? Did you do the test that way?

Chris

This post has been edited by C.R.Helmrich: Apr 12 2011, 20:17


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Garf
post Apr 12 2011, 21:44
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QUOTE
Please provide the number of valid results (i.e. listeners) per sample (excluding "27", see below).


Will be addressed when per sample graphs are made. You can obtain this data yourself easily if you can't wait - the results are public.

QUOTE (C.R.Helmrich @ Apr 12 2011, 21:11) *
[*]How did you compute the overall average score of a codec and its confidence intervals? Taking the mean of all listeners' results? That would mean a sample with more listeners (i.e. probably sample01) has a greater influence than the last few samples (which still needed listeners shortly before the end of the test). This is probably not a good approach; weighting each sample equally in the overall score seems to be the way to go for me (but it probably doesn't make a difference here, but still...).


This is already addressed and explained on the results page. Note that equal sample weighting, by only including complete results, does not change the results in the slightest.

That being said, the only solution to this is to put some infrastructure to force equal listeners per sample in the next tests. Any kind of post-processing to equalize the sample weights is probably as controversial as not having them equal in the first place. The samples that weren't included in the test also had unequal weights compared to those that were, if you know what I mean.


QUOTE
[*]Nothing personal, but if a listener like "27" consistently scores in opposite direction as the average (as shown by Igor), a thorough post-screening analysis (like Spearman rank correlation < some value) would - and has to - exclude such results.


As explained in this thread, this listener was in fact screened.
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C.R.Helmrich
post Apr 12 2011, 22:12
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Sorry, Christoph, can't reproduce it. What you describe must sound like a notch filter, i.e. frequency band missing. Haven't noticed anything of that sort during and after the test. What OS are you using? 64-bit?

Thanks, Garf and NullC, for the explanations.

QUOTE (Garf @ Apr 12 2011, 22:44) *
Note that equal sample weighting, by only including complete results, does not change the results in the slightest.

That's good to hear. Still, if you find some time, would you mind creating a closeup average-codec-score plot using only the complete results, just like the plot on the results page? rolleyes.gif

Thanks,

Chris


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Posts in this topic
- IgorC   Multiformat listening test @ ~64kbps: Results   Apr 12 2011, 00:40
- - Garf   If someone can assist with a bitrate table or per-...   Apr 12 2011, 01:02
- - Garf   Oh, and given that Opus is open sourced, if one of...   Apr 12 2011, 01:06
- - AllanP   I just wonder one thing, when the Vorbis encoder w...   Apr 12 2011, 01:14
|- - Garf   QUOTE (AllanP @ Apr 12 2011, 02:14) I jus...   Apr 12 2011, 01:15
|- - AllanP   QUOTE (Garf @ Apr 12 2011, 02:15) You can...   Apr 12 2011, 01:22
- - romor   Congratulation to CELT/Opus! I wanted to com...   Apr 12 2011, 03:08
- - IgorC   I think the results of lessthanjoey and AlexB are ...   Apr 12 2011, 03:50
- - googlebot   I'm stunned by the CELT/Opus results! I wo...   Apr 12 2011, 08:06
|- - NullC   QUOTE (googlebot @ Apr 11 2011, 23:06) I...   Apr 14 2011, 05:00
|- - saratoga   QUOTE (NullC @ Apr 14 2011, 00:00) We als...   Apr 14 2011, 06:29
||- - NullC   QUOTE (saratoga @ Apr 13 2011, 22:29) Is ...   Apr 14 2011, 08:30
|- - Garf   QUOTE (NullC @ Apr 14 2011, 06:00) Low-la...   Apr 14 2011, 12:19
|- - jmvalin   QUOTE (Garf @ Apr 14 2011, 07:19) Is the ...   Apr 14 2011, 14:04
|- - NullC   QUOTE (Garf @ Apr 14 2011, 03:19) QUOTE (...   Apr 14 2011, 17:47
|- - C.R.Helmrich   QUOTE (NullC @ Apr 14 2011, 18:47) The sw...   Apr 14 2011, 23:39
|- - jmvalin   QUOTE (C.R.Helmrich @ Apr 14 2011, 18:39)...   Apr 15 2011, 05:49
- - Alex B   Thanks guys! Interesting results. One note t...   Apr 12 2011, 12:59
|- - Garf   QUOTE (Alex B @ Apr 12 2011, 13:59) I got...   Apr 12 2011, 13:53
|- - NullC   QUOTE For processing the result .txt files with ch...   Apr 12 2011, 14:48
|- - Garf   QUOTE (NullC @ Apr 12 2011, 15:48) Sounds...   Apr 12 2011, 14:59
||- - Alex B   QUOTE (Garf @ Apr 12 2011, 16:59) But the...   Apr 12 2011, 15:09
|- - Alex B   QUOTE (NullC @ Apr 12 2011, 16:48) Sounds...   Apr 12 2011, 15:02
|- - NullC   QUOTE (Alex B @ Apr 12 2011, 07:02) QUOTE...   Apr 12 2011, 15:17
|- - motion_blur   QUOTE (Alex B @ Apr 12 2011, 16:02) QUOTE...   Apr 12 2011, 16:15
|- - NullC   QUOTE (motion_blur @ Apr 12 2011, 08:15) ...   Apr 12 2011, 17:54
|- - motion_blur   QUOTE (NullC @ Apr 12 2011, 18:54) QUOTE ...   Apr 12 2011, 19:42
- - Alex B   For comparison I uploaded a rar package of my ...   Apr 12 2011, 14:14
|- - Garf   QUOTE (Alex B @ Apr 12 2011, 15:14) For c...   Apr 12 2011, 14:49
- - Alex B   QUOTE (Garf @ Apr 12 2011, 16:59) But the...   Apr 12 2011, 15:35
|- - Garf   QUOTE (Alex B @ Apr 12 2011, 16:35) QUOTE...   Apr 12 2011, 15:42
- - Alex B   Regarding the bitrate table, I guess that CELT/Op...   Apr 12 2011, 16:14
|- - NullC   QUOTE (Alex B @ Apr 12 2011, 08:14) Regar...   Apr 12 2011, 18:10
- - IgorC   Yes, I was too strict. Sorry about it. Some of th...   Apr 12 2011, 18:13
|- - motion_blur   QUOTE (IgorC @ Apr 12 2011, 19:13) Yes, I...   Apr 12 2011, 20:09
|- - NullC   QUOTE (motion_blur @ Apr 12 2011, 12:09) ...   Apr 13 2011, 00:59
|- - motion_blur   QUOTE (NullC @ Apr 13 2011, 01:59) QUOTE ...   Apr 13 2011, 10:06
- - markanini   I figured ratings would vary between testers depen...   Apr 12 2011, 18:52
|- - NullC   QUOTE (markanini @ Apr 12 2011, 09:52) I ...   Apr 12 2011, 20:57
- - lessthanjoey   I've done some more testing with headphones af...   Apr 12 2011, 19:51
- - C.R.Helmrich   Thanks for organizing the tests, guys! Sorry f...   Apr 12 2011, 20:11
|- - motion_blur   QUOTE (C.R.Helmrich @ Apr 12 2011, 21:11)...   Apr 12 2011, 20:41
|- - Garf   QUOTE Please provide the number of valid results (...   Apr 12 2011, 21:44
||- - C.R.Helmrich   Sorry, Christoph, can't reproduce it. What you...   Apr 12 2011, 22:12
||- - Garf   QUOTE (C.R.Helmrich @ Apr 12 2011, 23:12)...   Apr 12 2011, 23:37
||- - motion_blur   QUOTE (C.R.Helmrich @ Apr 12 2011, 23:12)...   Apr 13 2011, 00:41
|- - NullC   QUOTE (C.R.Helmrich @ Apr 12 2011, 11:11)...   Apr 12 2011, 21:47
- - IgorC   motion_blur, You can download the results of all...   Apr 12 2011, 20:21
|- - _mē_   Some presentation suggestions: 1. Codec versions a...   Apr 12 2011, 20:43
|- - IgorC   QUOTE (_mē_ @ Apr 12 2011, 16:43) Some pr...   Apr 12 2011, 20:46
|- - Alex B   QUOTE (_mē_ @ Apr 12 2011, 22:43) 2. Link...   Apr 12 2011, 21:06
||- - Alex B   QUOTE (Alex B @ Apr 12 2011, 23:06) QUOTE...   Apr 13 2011, 11:38
||- - NullC   QUOTE (Alex B @ Apr 13 2011, 02:38) The b...   Apr 13 2011, 12:41
||- - Garf   QUOTE (NullC @ Apr 13 2011, 13:41) QUOTE ...   Apr 13 2011, 12:54
||- - Alex B   QUOTE (NullC @ Apr 13 2011, 14:41) Any id...   Apr 13 2011, 14:46
||- - NullC   QUOTE (Alex B @ Apr 13 2011, 05:46) QUOTE...   Apr 13 2011, 22:48
|- - Garf   QUOTE (_mē_ @ Apr 12 2011, 21:43) Some pr...   Apr 12 2011, 22:24
- - Alex B   Here is the raw data for a bitrate table. The bitr...   Apr 12 2011, 20:30
- - IgorC   Thank you for your help, AlexB. If you can do the ...   Apr 12 2011, 20:44
- - C.R.Helmrich   Christoph, do you mean the slightly washed out bas...   Apr 12 2011, 20:52
|- - motion_blur   QUOTE (C.R.Helmrich @ Apr 12 2011, 21:52)...   Apr 12 2011, 21:11
|- - C.R.Helmrich   QUOTE (motion_blur @ Apr 12 2011, 22:11) ...   Apr 12 2011, 21:38
|- - motion_blur   QUOTE (C.R.Helmrich @ Apr 12 2011, 22:38)...   Apr 12 2011, 21:56
- - IgorC   I've checked. The decoder on Christoph's s...   Apr 12 2011, 20:54
- - Alex B   Here's the bitrate table: In Excel format: ...   Apr 12 2011, 22:20
|- - saintdev   QUOTE (Alex B @ Apr 12 2011, 14:20) Here...   Apr 12 2011, 23:21
- - NullC   QUOTE (IgorC @ Apr 11 2011, 16:40) The te...   Apr 13 2011, 04:42
|- - Garf   QUOTE (NullC @ Apr 13 2011, 05:42) Hey al...   Apr 13 2011, 08:27
||- - IgorC   QUOTE (Garf @ Apr 13 2011, 04:27) One thi...   Apr 14 2011, 05:57
|- - C.R.Helmrich   Thanks, Garf, for the plot! And thanks, Christ...   Apr 13 2011, 22:46
|- - Garf   QUOTE (C.R.Helmrich @ Apr 13 2011, 23:46)...   Apr 13 2011, 22:57
||- - C.R.Helmrich   QUOTE (Garf @ Apr 13 2011, 23:57) From th...   Apr 13 2011, 23:06
|- - jmvalin   QUOTE (C.R.Helmrich @ Apr 13 2011, 17:46)...   Apr 14 2011, 00:58
|- - Garf   QUOTE (jmvalin @ Apr 14 2011, 01:58) I do...   Apr 14 2011, 09:13
|- - jmvalin   QUOTE (Garf @ Apr 14 2011, 04:13) You are...   Apr 14 2011, 11:41
- - Garf   The result page is now updated with per-sample gra...   Apr 13 2011, 12:41
- - mixminus1   Thanks much to all for their work in both setting ...   Apr 13 2011, 14:55
|- - Garf   QUOTE (mixminus1 @ Apr 13 2011, 15:55) Th...   Apr 13 2011, 15:04
- - mixminus1   :facepalm: Good God... Thanks, Garf, I was scour...   Apr 13 2011, 15:15
- - romor   @Garf: can you please reupload results you posted ...   Apr 13 2011, 16:35
|- - Garf   QUOTE (romor @ Apr 13 2011, 17:35) @Garf:...   Apr 13 2011, 18:59
- - IgorC   AlexB, thank you for bitrate verification. I real...   Apr 13 2011, 17:12
- - pdq   Whether or not classical should be considered to b...   Apr 13 2011, 17:51
|- - IgorC   QUOTE (pdq @ Apr 13 2011, 13:51) Whether ...   Apr 13 2011, 18:01
|- - pdq   QUOTE (IgorC @ Apr 13 2011, 13:01) QUOTE ...   Apr 13 2011, 18:53
- - romor   file: http://people.xiph.org/~greg/opus/ha2011/2.....   Apr 13 2011, 19:28
|- - NullC   QUOTE (romor @ Apr 13 2011, 10:28) file: ...   Apr 13 2011, 19:53
- - IgorC   Bitrate verification on my set of albums: http:/...   Apr 13 2011, 21:45
|- - NullC   QUOTE (IgorC @ Apr 13 2011, 13:45) Bitrat...   Apr 21 2011, 19:15
|- - jmvalin   QUOTE (NullC @ Apr 21 2011, 14:15) QUOTE ...   Apr 21 2011, 19:53
- - Garf   QUOTE Has anyone ever seriously blind-tested e.g. ...   Apr 14 2011, 00:10
|- - C.R.Helmrich   QUOTE (Garf @ Apr 14 2011, 01:10) I'm...   Apr 14 2011, 10:46
- - .alexander.   The second graph seems to be consistent with ...   Apr 15 2011, 12:40
|- - jmvalin   QUOTE (.alexander. @ Apr 15 2011, 07:40) ...   Apr 15 2011, 15:17
- - Xanikseo   QUOTE (IgorC @ Apr 13 2011, 21:45) Bitrat...   Apr 20 2011, 16:34
|- - Garf   QUOTE (Xanikseo @ Apr 20 2011, 17:34) Igo...   Apr 20 2011, 18:02
|- - IgorC   QUOTE (Xanikseo @ Apr 20 2011, 12:34) Igo...   Apr 20 2011, 18:19
|- - Zarggg   QUOTE (Xanikseo @ Apr 20 2011, 11:34) EDI...   Apr 20 2011, 19:09
- - Xanikseo   QUOTE (Zarggg @ Apr 20 2011, 19:09) QUOTE...   Apr 20 2011, 21:20
- - IgorC   NullC, h*tp://www.mediafire.com/?s7i9usu2qr27pcg ...   Apr 21 2011, 23:52
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